As shown in my copending application Ser. No. 889,393, film forming aromatic polyformals can be made having up to about 50% by weight of cyclic polyformals of the formula, ##STR1## where R is a divalent aromatic organic radical, and n is an integer equal to from 2-25 inclusive, by agitating a mixture of methylene halide, bisphenol, alkali metal hydroxide with either a phase transfer catalyst or a dipolar aprotic solvent.
The cyclic polyformals of formula (1) have been found to be useful for making wire coating formulations when employed in combination with a Lewis Acid catalyst and an organic solvent.
The present invention is based on the discovery that aromatic cyclic polyformals of the formula, ##STR2## where n is an integer equal to 2-25 inclusive, can be made by my aforedescribed method utilizing 1,1-dichloro-2,2-(4-hydroxyphenyl)ethylene or "dichloride" as the bisphenol. The aromatic cyclic polyformals of formula (2) also can be used to make wire coated formulations when employed as an organic solvent solution with a Lewis Acid catalyst, such as FeCl.sub.3, H.sub.2 SO.sub.4, etc.
Another procedure which can be used to make aromatic cyclic polyformals of formula (2) is shown in the above described copending application Ser. No. 905,635, of Donald S. Johnson. In accordance with the procedure of Ser. No. 905,635, a bisphenol dianion is utilized in an aqueous phase at up to about 3% by weight in combination with excess alkali metal hydroxide, which in employed in further combination with a phase transfer catalyst and an organic phase comprising methylene chloride. The aqueous phase and the organic phase are maintained at about equal parts by volume while the mixture is agitated.
In addition to making wire coating formulations, the aromatic cyclic polyformals of formula (2) also can be blended with various organic polymers, such as polycarbonates, polyesters, etc., at proportions of from 1% to 25% by weight, resulting in thermoplastic materials having improved flame retardant properties.